1. Field of the Invention
The present invention is directed to a method and arrangement for controlling a dynamic scale which allow fast mixed mail processing in a franking system. The method is suitable for users of mail processing systems with a dynamic scale and postage-calculating postage meter machine, or with dynamic postage calculating scales and franking devices.
2. Description of the Prior Art
U.S. Pat. No. 4,956,782, British Specification 22 35 656 and European Application 514 107 disclose semi-dynamic weighing. Transport is interrupted, particularly given large postal matter that is difficult to weigh. The transport speed is reduced dependent on the dimensions of the letter.
For fast mail processing in a postage meter machine, U.S. Pat. No. 4,935,078 (corresponding to European Applications 615 212 and European Application 615 213) discloses a time control according to an operating mode selected for the user stations by the user. The user station arranged upstream can be a scale and the user station arranged downstream is the postage meter machine. A letter length is determined with sensors and the control of the user station arranged upstream and is transmitted to the postage meter machine. The latter controls the preceding, dynamic scale, so that the letter transport speed is reduced dependent on the letter length. A disadvantage is the reduced throughput for all long letters. Such scales require a modification of the control of the postage meter machine. There is the risk of letter jams given a high item input.
Known scales of the GFI Company are dynamic scales that require a reject compartment for incorrectly weighed letters. These incorrectly weighed letters are transported but are not franked. Incorrect weighing can occur because of an unstable environment and the fact the center of gravity of the letter, particularly given long letter formats, arrives too late on the scale, so that the weighing time is too short. These letters must then be separately weighed with a suitable, static scale. The corresponding postage must then be manually inserted into the franking unit. The automatic executive sequence is thus interrupted. Especially disadvantageous is the fact that the mail shipper cannot predict whether a specific letter that is placed together with the others as a stack will exceed these weight limits.
Given mixed mail, the probability is higher that the scale an incorrect weighing will occur. The throughput given mixed mail is reduced because either the speed is reduced or incorrectly weighed letters are rejected. Controllable motors and a complicated controller are required in order to be able to reduce the speed.